tornado.curl_httpclient now works on Python 3 with the
soon-to-be-released pycurl 7.19.3, which will officially support
Python 3 for the first time. Note that there are some unofficial
Python 3 ports of pycurl (Ubuntu has included one for its past
several releases); these are not supported for use with Tornado.

Malformed x-www-form-urlencoded request bodies will now log a warning
and continue instead of causing the request to fail (similar to the existing
handling of malformed multipart/form-data bodies. This is done mainly
because some libraries send this content type by default even when the data
is not form-encoded.